The formation of volatile Si-O-H species from silica occurs in water-vapor containing environments such as combustion environments. In this paper the pressure and temperature dependence of known Si-O-H species are surveyed. Trends based on the number of water molecules incorporated in the Si-O-H species are identified. Larger molecules (more OH groups) tend to have a higher pressure dependence and lower temperature dependence. These trends are then used to identify possible unknown species observed in high pressure fuel-rich combustion environments.